With the development of semiconductors in recent years, portable electronics and flat-panel displays have emerged as well. Among the various types of flat-panel displays, the Liquid Crystal Display (LCD) has become mainstream for its low operation voltage, absence of radiation scattering, light weight and small volume. This is why every factory focuses on developing LCD with smaller size and lower cost.
To lower the manufacturing cost of LCD, the shift register may be transferred from inside the gate driver onto the glass substrate of the LCD panel. A scanning signal (e.g. main gate signal or secondary gate signal) is outputted during operation of the shift register to activate a corresponding row of pixels in the LCD panel. Typically, the shift register manufactured on the glass substrates is made of a number of thin film transistors (TFTs). Due to the restrictions of manufacturing process, the electric property of the thin film transistor may cause the driving ability of the shift register to be insufficient. Therefore, finding a way to enable the shift register made of thin film transistors to work properly has become an important topic in the design of shift registers.